Traditionally doors are made of metal (typically steel), solid wood (solid core) or wooden framing and boards (hollow core). Typically modern doors are constructed relatively cheaply by placing a wooden or laminate cladding over a structured or ‘honeycomb’ core.
Solid core doors require a large amount of quality timber, and given the increasing pressures to reduce consumption of quality timber trees are becoming increasingly expensive and environmentally unacceptable.
Metal doors, especially steel doors, although strong and fire resistant, are relatively heavy, expensive to produce compared to wooden doors, and cannot be adapted on site to suit a particular size of frame or application.
Furthermore, hollow or structured core timber doors do not intrinsically posses the high thermal insulation required to resist or prevent the spread of fire, and must be laminated or clad with various fire resistant materials to increase inflammability, which can significantly increase production costs.
Also, sound insulation properties of wooden hollow and structured core doors are typically poor such that additional sound insulating materials can be required.
In addition, wooden hollow or structured core doors have poor water resistant properties, and will tend to delaminate, warp or swell when consistently exposed to water or humidity, such as in wet, tropical or subtropical conditions e.g. high humidity, high rainfall. Even in temperate conditions, if exposed to rain or humidity, such doors have a short lifespan.
Low cost doors are also prone to change in shape and dimensions, typically due to warpage or shrinkage.
Metal doors are prone to corrosion when exposed to wet weather and/or high humidity for prolonged periods.
Ceramic boards per se are known in the building and construction industry. Generally the most common boards are gypsum boards, cement fibre boards, glass reinforced cement (GRC) or glass reinforced gypsum (GRG), and calcium silicate boards. Such boards are typically manufactured between 3 mm and 25 mm thick, and are basically flat sheets with density ranging from 800-1800 kgm−3 with the exception of GRC which has a bulk density of 2200-2500 kgm−3.
Cement is a fine calcinated powder typically containing silica, alumina, calcium oxide (lime) and often iron oxide(s) and magnesia. Gypsum is finely divided calcium sulphate usable as a calcinated powder.
Traditionally, wall partitions use purely gypsum boards for general use. These are relatively low in cost to manufacture and install but are not waterproof and have low security being soft.
However, should waterproofing be required, cement or GRC fibreboards are used. Cement fibreboards cannot be fire rated due to inherent shrinkage of cement and high content of organic cellulose fibre which is removed from the cement fibreboard at temperatures above 300-400° C. Such boards typically undergo cracking and structural failure at high temperature.
Similarly, GRC boards suffer from cement shrinkage at high temperature regardless of the glass fibre content.
GRG boards typically include gypsum, fillers and glass fibres. These boards can be fire rated but are not waterproof due to the high gypsum content and are relatively soft. They are therefore generally used for internal applications, such as plaster ceiling boards where they are not subject to dampness or pressure.
Subsequently, calcium silicate boards have been developed. However, these require increased investment in manufacturing plant and machinery, such as autoclaves and steel drum rollers etc, and are therefore more expensive to manufacture than other boards.
Previously, lightweight doors and door cores using cement and/or gypsum have been proposed. For example, GB 2250282 and GB 2266912 by the same inventor of the present invention disclose applications of a door or core board for a door made of lightweight set and hardened material based on cement and/or gypsum. Lightweight characteristics are achieved by having large voids in the board and/or addition of lightweight particulate or fibrous material. However, the resulting board has a resulting typical bulk density of only 400-700 kgm3. Such a lightweight material tends to be brittle and crumbly, and subject to chipping, cracking particularly at the edges thereof, thereby requiring edge support in the form of wooden or metal framing to add strength and reduce the risk of damage or failure of the door board.
Further, cabinet hinges are specially made for light, thin timber based doors which are usually particleboard, chipboard, MDF, HDF, blockboard of thickness of 10 mm to 30 mm. Their main applications have been kitchen cabinets, office cabinets, wardrobe, furniture etc., where sizes are 900/1200 high by 600/800 wide or 800/900 wide by 2100 height for full size wardrobe doors.
Such hinges are suitable for timber based doors because timber density is 400-800 kg/m3 (fairly light); but more importantly timber is an excellent medium for holding fast wood screws.
For certain designs, the cabinet hinges have been used to mount glass. The only two practical ways commonly adopted is to either use an outer timber board surrounding the glass and mount the cabinet hinges in the timber based board like usual cabinet doors, or to custom make metal ‘patch fittings’—similar to bathroom shower doors—where the glass board is sandwiched between 2 metal ‘patch fittings—where cabinet hinges are required to be used. The out facing ‘patch fittings’ is highly finished and the internal one is with custom recesses, holes to mount the cabinet hinge.
To date, there has been no requirement to use ceramic boards to mount cabinet hinges mainly because                1. these boards are usually more costly than timber based boards,        2. gypsum cement fibre, calcium silicate boards are heavier: 800-1600 kg/m3, however, weight is a serious disadvantage when using cabinet hinges,        3. workability of the ceramic boards is more difficult then timber based boards—e.g. powdery face makes it hard to paint/veneer, delamination, poor adhesion, edges usually hard to finish off as most boards have jagged edges when sawn due to its brittleness/hardness.        4. cannot hold screws—unlike timber based boards, ceramic boards cannot be held secure solely on the screw threads, but require to be sandwiched between the countersunk screw head and steel studs/timber joints. All ceramic boards made to date are for fixed non-moving uses like walls partitions and ceilings.        
Cabinet hinges need to be recessed into a board and require the board to be able to hold screw threads. Most hinges require 8-12 mm recess. As such, the board must be thicker than 8-12 mm, and able to hold screw in its remaining thickness.
Based on current existing boards, this would require 16-30 mm thick boards. As the lightest boards come in densities 800-1600 kg/m3—double that of timber based boards, the weight would be double.
In normal furniture and cabinets, a 2-3 mm thick PVC edge strip is typically used to protect the edges of the doors. Door thickness are typically 12-16 mm which allows enough width to glue on the PVC strip or to allow a groove to be routed into the 12-16 mm wide door edge. The groove receives a projection moulded onto the back of the PVC strip to provide better attachment of the strip.
The present invention is concerned with ceramic door, door boards or wall boards constructed from compositions containing at least gypsum, cement and preferably additional materials, in selected proportions which result in a product which alleviates the aforementioned detrimental structural and/or application characteristics of the aforementioned boards.
Using normal known panels it is difficult to finish off and/or protect the edges. This is because most known boards are laminated to give strength and rigidity e.g. plastic laminate sandwiching chipboard, and to receive face fixings. When a 18-30 mm board is used as a partition, door or wallboard, and the edge of the board stops an opening where there is traffic or movement, a capping or protector is required for the edges to prevent chipping, fraying and damage. Currently a thin aluminium channel would be capped over the edge of the board and screwed form the face or back. This provides an unsightly fixing with exposed fixings and which may not be retained very well in the panel.